The present invention relates to a power connector for a substrate. More specifically, the present invention relates to a zero insertion force power connector for a substrate with an edge-type connector. The present invention further relates to a method for creating a power connection for a substrate and, more specifically, a method of using a zero insertion force socket by actuating an actuator to increase the normal force between the substrate metal contacts and the socket contacts.
Edge-type power connections are commonly used for integrated circuits. These connections often consist of the edge of the substrate upon which an integrated circuit is etched, deposited or otherwise arranged. The substrate may have an organic composition and is generally planar. The substrate may be both flexible, with respect to bending or breaking forces, and rigid, with respect to compressive loads. Arranged on an edge of the substrate may be a metal contact area. This metal contact area may consist of a zone of metal plating on the surface of the substrate extending along the edge of the substrate. Alternatively, this metal zone may be situated on both sides of one edge of the substrate. This metal contact area is connected to the integrated circuit and provides power for the circuit. The electrical contact on one side of the substrate may be electrically coupled to the electrical contact on the other side of the substrate. Such a substrate with edge contacts may be referred to as an edge-type substrate.
Power connections generally use a contact design in which a socket contact, or numerous socket contacts, engage a substrate metal contact, or numerous metal contacts, with some insertion force. Within the socket (socket housing), there may be spring loaded contacts (socket contacts) or fingers (socket fingers) that contact the metal pads (metal contacts) of the substrate to provide power delivery to the substrate. When the socket engages the substrate, the socket fingers are deformed, and an insertion force must be applied to the substrate in order to push the substrate further into the socket to overcome the resistance imposed by the deformation of the socket fingers. When the substrate bottoms out in the socket, the socket fingers reach their final positions. The deformation of the socket fingers provides a normal force between the substrate and the socket that reduces the DC resistance of the power connection. The DC resistance is the resistance of the system to a direct current as motivated by a constant voltage.
In certain substrate edge power delivery solutions, when the package edge connector is inserted into the socket, the contacts resist the substrate movement, thus creating an insertion force. This insertion force can bend or even break the substrate, thus damaging the integrated circuit. Since the insertion force is limited by the substrate mechanical strength, which is often limited by the integrated circuit manufacturing process, the normal force of the connector is also limited. Therefore, traditional edge type power connectors are limited in their ability to reduce the DC resistance at the contacts between the substrate and the socket.
A conventional power connection is illustrated in FIGS. 1A and 1B. FIG. 1A illustrates a substrate 101 with an integrated circuit having metal contacts 102 on both sides of an edge to provide power to the integrated circuit. Two socket contacts 104, also referred to as socket fingers, are enclosed within socket 103. Socket contacts 104 are arranged in opposition to each other within socket 103. Additional socket contacts may be situated adjacent to socket contacts 104, such that a line of socket contacts extends on both sides of socket 103, the two lines extending parallel to the opening of the socket and the edge of substrate 101. The gap between socket contacts 104 is smaller than the width of substrate 101. Therefore, an amount of force is required to insert substrate 101 into socket 103 when moving substrate 101 in the direction of arrow 105. As metal contacts 102 on substrate 101 pass between socket contacts 104, socket contacts 104 are deformed slightly since substrate 101 is not easily compressible. Therefore, as substrate 101 is pushed into socket 103, socket contacts 104 are deformed outwardly. The deformation of socket contacts 104 provides a normal force in the power connection between socket contacts 104 and metal contacts 102.
FIG. 1B illustrates substrate 101 completely inserted into socket 103. Socket contacts 104 have deformed slightly to allow passage of substrate 101 that includes metal contacts 102. Socket contacts 104 resist deformation and therefore resist insertion of substrate 101. Due to the limited rigidity of substrate 101, the amount of deformation and resistance is therefore also limited. Thus, if the deformation, and therefore the resistance, is increased beyond a certain limit, substrate 101 may bend and/or break in response to the resistance to insertion imposed by socket contacts 104 when substrate 101 is inserted into socket 103. This limitation on the deformation of socket contacts 104 translates into a limitation on the normal force between socket contacts 104 and metal contacts 102.
Zero insertion force (ZIF) connectors for pins have been utilized to increase the normal force on the pin and thereby decrease resistance to the signal being transmitted through the pin connector. ZIF pin connectors have included rings as the connectors for the pins. After insertion of the pin into the socket, actuation may either close the ring around the pin or move the pin against the substantially stationary ring. Increased normal force for pin connectors may lower DC resistance for a signal, which may result in a better signal to noise ratio.
An object of the present invention is to provide a zero insertion force power connector for edge-type substrates, and to thereby decrease the mechanical strength requirements of the substrate and decrease the resistance, and therefore the power loss, in the power connection.